The proposed research examines the basic processes and mechanisms underlying children's coping with the stress of medical and dental procedures. The character of cognitive processing is observed in three studies of normal children undergoing routine dental restorative treatment. The first looks at children's ability to use imagery to prepare for dental stress. The second evaluates the parallel structure of the fear response in imagery and during actual exposure. The third explores therapeutic intervention based on the identified manifestation of the fear response. A bioinformational theory is employed to explain the data from physiology, developmental, and behavioral perspectives of fear. The prediction of optimal treatment strategy is based on theory. The second focus examines the influence of children's relationship with parents during the immediate preparation for medical examinations and during these examinations. There are few reports of normative fears in children that are based upon direct observation. Many of the studies derive from parental, primarily maternal, report of what the child fears. It is also well established that parental anxiety may influence their children's adjustment to stress. Therefore, a dyadic prestressor observational scale was devised from the theoretical developmental literature. Cross-sectional evaluation of children (4 to 6, 7 to 9, 10 to 12) will allow for the actual test of developmental change in fear of medical events in children of varying cognitive abilities, social class, and reinforcement histories. The need to identify children whose fears may lead to problems in health care utilization requires a normative data base. The relationship between early cooperation and attitudes regarding medical treatment is likely to influence long-term access to health care. The pattern of interactions between parent and child that facilitate cooperation and reduce fear will be identified taking the age of the child into account.